Photographic multilayer stripping films



Sept. 2, ,1952

J. H. coo-rs ET AL 2,609,291

PHOTOGRAPHIC MULTILAYER STOPPING FILMS Filed Nov. 26, 1948 BLUE SENSITIVE EMULSION LAYER YELLOW FILTER LAY'ER SECOND $UBB.ING LAYER SECOND COPOLYMER LAYER GREEN SENSITIVE EMULSION LAYER FIRST SUBBING LAY FIRST EOPOLYMER LA IIED SENSITIV'E EMULSION LAYER YER EELLULOSE NITRATE BASE MATERIAL.

Inventor.)

G"fi; Mal/dam arn) gQJXgM Patented Sept. 2, 1952 PHOTOGRAPHIC MULTILAYER STRIPPING FILMS Jack Howard Coote, London, andWilliam Harry.

Gathercole, Surrey, England,

assignors to Dufay-Chromex Limited, London, England, a 1' British company Application November 26, 1948, Serial No. 62,226 J In Great Britain November 28, 1947 7 Claims.

This invention relates to multi-layer stripping films and to a process for the production thereof- Such films are required when it is desired to transfer one or more of a plurality of colour records produced by a single exposure to separate bases for use in obtaining the corresponding positive records or for use in the copying process described in British patent specification No. 638,308.

For use in motion picture work it is necessary to secure good adhesion between the several layers as well as good overall flexiblity with the minimum thickness of film. It is diflicult to secure material fulfilling, allthese requirements.

Numerous proposals have been made to interpose between silver halide emulsion layers substances of basic -or acidic character (usually applied as solutions in organic solvents) and to rely upon the ultimate solution in an aqueous bath of approporiate pH of the basic or acidic substance to permit ready separation of the emulsions with or without a supporting layer. Other proposals have included the application of solutions in organic solv'ents or even in water of filmf-orming substances'ito provide interlayers having adhesive properties.

We have now found that multi-layer stripping film meeting the. basic requirements for motion picture work and which can be accurately con trolled is obtained when the layer or layers separating the silver halide emulsion layers comprise a copolymer of vinyl chloride and vinyl acetate. The copolymers can be coated from solutions in volatile organic solvents which can be satisfactorily. removed at low temperatures. The layers are hydrophobe and resist penetration by aqueous liquors. They also have good overall flexibility and can be coated in thin layers. They can be applied and'the solvents evaporated under conditions which do not harm the underlying silver halide emulsion layer or layers;

The present invention provides a multi-layer stripping film comprising a support carrying upon one side thereof at least two silver halide emulsion layers sensitive to difierent parts of the spectrum, said layers being separated by a layer comprising a hydrophobe copolymer of vinyl chloride and Vinyl acetate.- Preferably the copolymer employed has a molecular weight of approximately ten thousand and contains about 35-88% of polyvinyl chloride. 7

According to a feature of the invention the layer comprising the copolymer of vinyl chloride and vinyl acetate also contains interpolymer-ized therewith a small amount of an aliphatic hy- (Cl. 95-2) I droxy dicarboxylic acid such by weight. 1 In carrying outthe process of the invention the base material carrying a first silverhalide emulsion is coated with a'thin layer of a solution in volatile organic solvents ofa coplymer of vinyl chloride and vinyl acetate. tion may beusedr 'Parts by weight Copolymer A 16.0 Copolymer B 16.0 Acetone 48.0. Benzene 20.0

Copolymer A was a copolymer of vinyl-chloride and vinyl acetate having a molecular weight of about ten thousand and containing between and 88% of'vinyl chloride. Cjop'olymer B was a Whena three layer material is to be produced the material is againcoated with the solution of copolymer, dried as'b'efore and then treated, after drying, with a dilute aqueous solution of gelatine and chrome alum containing a wetting agent. It

is then coated with the third silver halide emulsion layer.

The copolymer layers are quite' impermeable to the usual photographic processing reagents andafter a multi-layer film produced as above described has been'exposed the individual layers can be developed, the images copied using infrared light as outlined in U. S. Serial No. 42,351 and then stripped ofi' carried upon the copolymer layer. It is not necessary to use special solvents to reduce the adhesion between the layers, which,

as laid down; havesufficient adhesion to hold, them together. duringprocessing of the material as well as the necessary flexibility, but can be.

readily separated and peeled apart without-damaging the underlying emulsion layer.

asmalic acid. Usu- I ally the amount or acid is between. 0.5 and 2.

The following solu- It has been found quite satisfactory to use a single standard solution of copolymer for the stripping layers when more than one is required.

There will now be described the production of a three colour stripping film in'accordance with. the invention. This is illustrated in the accompanying drawing.

A cellulose nitrate base I carrying a red sensitized silver halide emulsion layer lwas coated with a thin coating of the solution of copolymers A and B described above. The solvents were gradually removed in a current-oi warm air, care. being taken to keep the temperatureeof the-air -below 90 F. and preferably between 70- and 80 F. The resulting layer of copolymer '3 was about five ten-thousandths of an inchzthickx After ,re- 7 moval of the solvents the surface treated Twithra subbing solution made up from equal volumes of 1% aqueous solutions of .chrome alum and gelatine to which had been added a small quantity of a wetting agent. The subbinglayerl-is' thencoated with the green'sensitive silver halideemulsion layer 5. The emulsion as applied -hadprev-iously had added to it -a*small-*quantity of a wetting"-agentabout 0.10% byweight based upon the weight of the emulsion-'hasbeen found 'to be suitable: The'wetting agentisfound toassist inspreadingthe gelatine emulsion;

The green sensitive silver halide emulsion layer 51s ,then'coatedwith a thin layer of the same solution of copolymers-A and B; the poating'bc lug-appliedinsuch aquantity'as to produce;

upon drying; a layer-cf about five-ten-thou-" sandths of an inch-thickness.-= The coating 'was dried with warm air as before and the resulting layerpf copolymer '6 treated with the same subhing; solution as, that previously employed. The resulting subbing ;layer his then coated with a. layerof gelatine 8 dyed with .Chlorazol Brilliant- Yellowto serve-as a minusiblue filter. Finallya blue 'sensitivc silver halide. emulsion-layer 9 containing a small; proportion of wetting agent is coated upon the yellow filter layer.

In an alternative procedure instead-poi insertlng-the-minus blue filter. as a, separate-layer a yellow dye mayybe added to the :solution of the copolymerofvinyl chloride and..viny1 2 acetate which is applied over i the. green sensitive silver halideemulsion layer. A suitable dye is: Waxoline'Yellow IS.

There-is thusprcduced athree colour-stripping film inwhich the outermost and middleemulsion layers can each be stripped. off carried/upon the underlying copolymer layer. No specialchemicals arerequired to reduce=the adhesionbetween the layers and since the copolymer.layers are impermeable to thenormal photographic vdee velopers, no. special. arrangements. such. as ac:- curatetiming inthe application of the. developers are necessary to prevent undue penetration.

support'carrying upon onerside thereof 'at least. 5

two silver. halide emulsion layers sensitive to. dif-' ferent. parts of 'the'spectrum; saidlayers being separatedby a layer comprising-a transparent: flexible, water-insoluble, hydrophobe copolymer of1viny1 chloride and vinyl acetate'and' contain- P ing atleast 85% of vinyl chloride; the silver halide emulsion layer 'underlying fsaid copolymer'" layer adhering directly to said copolymerlayer and the silver halide emulsion layer overlying said copolymer layer being attached hereto by a of-vinyl chloride and vinyl acetate having a molecular weight of about 10,000 and containing 85%-88% of vinyl chloride, the silver halide emulsion laycr underlying said copolymer layer adhering directly to said copolymer layer and the silver-halide-emulsicn layer overlying said copplymer: layer-being attached thereto by a hardenedsgelatine layer.

3.A,multi-layer stripping film comprising a support carrying upon one side thereof at least two silver halide emulsion layers sensitive to different :parts oi -the spectrum, said layers being separatedbya layer: comprising a transparent, flexible, water-insoluble, hydrophobe copolymer of vinyl chloride-and vinyl acetate having a mo- I lecularweightof about. 10,000 and containing 859648895 oi vi-nyl'chloride and having interpolymerited;therewithw0;5-2;5% -by weight of an aliphatic hydroxy dicarboxylic acid, the silver halide emulsion layer underlying said copolymer layeradhering:- directly to said copolymer layer andthe silver halide emulsion layer overlying said bopolymer layer beingiattachedgthereto by a hardened gelatine layer:

4. A multi-layer:strippingfilm according to claim-3 in: which the aliphatichydroxy dicarboxylic 'acid ismali'c-aoid;

EJA multi-layer stripping film comprising a support carrying upon one :side thereof three silver halide emulsion layers; each sensitive to ahilterenhpart of the spectrum; each adjoining pair: of emulsions. layers. being; separated by a layer'comprisingantransparent, flexible, waterinsoluble, hydrophobe: copolymer of vinyl chloride'and vinyl acetate-containing at least 85% orvinyl chloride, the silver'halide .emulsion layer underlying each of said copolymer layers-adheringdirectly theretoandthe. silver halide layer overlyingteach' oit'saidcopolymer layers being attached: thereto by a: hardened gelatine layer.

61A". multislayer. strippingfilm according to claim 51in .whichat least one copolymer layer is dyed to act'as a light filter.

'7. A: multi-layerl stripping, film according to claim :5 in which there is: interposedbetween a copolymer" layer, and the outer of the silver halidezemulsion layers that'rit' separates, a dyed gelatine layer; which acts as'azlight filter.

JACKiHOW-ARD COOTE. WILLIAM:HARRY:GAII-IERCOLE.

annsanncnsorrnn Thefollowing references are of record in the fileofthis patent:

UNITED STATES PATENTS Number Name Date 2,010,188 Hagedorrret al.- Aug. 6,1935 2,167,732. Verkinderen Aug. 1, 1939 2,182,814. Marascow"; .Dec. 12, 1939 2,293,8161 Glafkides; .Aug. 25,- 1942 2,415,442 Rackett Feb. 11, 1947 2,448,552 Schulze:: ,Sep t.' 7,1948 

1. A MULTI-LAYER STRIPPING FILM COMPRISING A SUPPORT CARRYING UPON ONE SIDE THEREOF AT LEAST TWO SILVER HALIDE EMULSION LAYERS SENSITIVE TO DIFFERENT PARTS OF THE SPECTRUM, SAID LAYERS BEING SEPARATED BY A LAYER COMPRISING A TRANSPARENT, FLEXIBLE, WATER-INSOLUBLE, HYDROPHOBE COPOLYMER OF VINYL CHLORIDE AND VINYL ACETATE AND CONTAINING AT LEAST 85% OF VINYL CHLORIDE, THE SILVER HALIDE EMULSION LAYER UNDERLYING SAID COPOLYMER LAYER ADHERING DIRECTLY TO SAID COPOLYMER LAYER AND THE SILVER HALIDE EMULSION LAYER OVERLYING SAID COPOLYMER LAYER BEING ATTACHED HERETO BY A HARDENED GELATINE LAYER. 